outpost are there to battle taliban coming in from afghanistan. >> reporter: kunar in eastern afghanistan is some of the toughest terrain america has troops in here. you can see this particular base is surrounded by hills on either side, which give the insurgency a central vantage point from which they can attack. the base violence is so consistent it makes it very hard for them to have the kind of contact with locals they need. life here really a waiting game for the worst to happen. everywhere you look, here in kunar on afghanistan's eastern border, the choices aren't good. outpost king is caught between hills full of taliban. if the americans leave, militants from pakistan will flow through the valley. if they stay, every few days this happens. the mortars hit the base. the last attack was long enough ago there's panic, they're worried the taliban have been preparing a big one. after days of nothing, the insurgents are finally beginning an attack from all sides. >> fire. >> command hustle up, grab it and get ready. >> reporter: they use mortars first, aiming for taliban dark into the h